Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare it is a non-read-only, non-destructive, non-idempotent operation, and the description adds the crucial human-in-the-loop detail: it returns a link the user must approve in the browser, plus a code they must be shown. This return-shape disclosure is valuable given there is no output schema, though failure modes and link expiry are unstated.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, front-loaded with the purpose, then the prerequisite, then the next step. The first sentence is compressed into a semicolon clause but nothing is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a signup-initiation tool with a nested details object and no output schema, the description supplies the key missing pieces: what the call returns (link and code), that the user must approve it, and what to call next. Only error and retry behavior is left implicit.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all five parameters are already documented, including the 'ask, do not guess' instruction on found_us. The description restates the data_wanted and use_case requirements at a high level without adding format or constraint detail, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and outcome ('Starts getting a free API key') and names the follow-up sibling finish_signup, so the agent can place it in a two-step flow. It stops short of distinguishing itself from complete_setup or the other setup-adjacent siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear contextual guidance: only call it once you know what data the user wants and their use case, ask rather than guess, then call finish_signup. There is no explicit when-not-to-use or comparison against complete_setup.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.